Debt - Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Outstanding balance	$ 56,387	$ 49,715
Unamortized Underwriting Fees	(135)
Long-term Debt
Debt Instrument [Line Items]
Outstanding balance	$ 56,387	$ 49,715
Year-End Stated Rate on Debt (as a percent)	4.72%	4.51%
Unamortized Underwriting Fees	$ (135)	$ (96)
Parent Company
Debt Instrument [Line Items]
Outstanding balance	42,787	35,312
Fixed Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 9,865	$ 14,582
Year-End Stated Rate on Debt (as a percent)	3.79%	3.66%
Year-End Interest Rate with Swaps (as a percent)	3.94%	3.80%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | American Express Credit Corporation
Debt Instrument [Line Items]
Outstanding balance	$ 336	$ 333
Year-End Stated Rate on Debt (as a percent)	3.30%	3.30%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%
Fixed Rate Senior Notes | Subsidiaries | Long-term Debt | Lending Trust
Debt Instrument [Line Items]
Outstanding balance	$ 13,181	$ 13,934
Year-End Stated Rate on Debt (as a percent)	4.72%	4.23%
Year-End Interest Rate with Swaps (as a percent)	4.63%	4.32%
Floating Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 3,650	$ 3,000
Year-End Stated Rate on Debt (as a percent)	4.80%	5.49%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%
Fixed-to-Floating Rate Senior Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 27,445	$ 15,973
Year-End Stated Rate on Debt (as a percent)	5.07%	5.35%
Year-End Interest Rate with Swaps (as a percent)	4.98%	5.57%
Fixed-to-Floating Rate Subordinated Notes | Parent Company | Long-term Debt | American Express Company
Debt Instrument [Line Items]
Outstanding balance	$ 1,771	$ 1,742
Year-End Stated Rate on Debt (as a percent)	5.44%	5.44%
Year-End Interest Rate with Swaps (as a percent)	5.36%	5.80%
Floating Rate Borrowings | Subsidiaries | Long-term Debt | Other Subsidiaries
Debt Instrument [Line Items]
Outstanding balance	$ 275	$ 247
Year-End Stated Rate on Debt (as a percent)	1.18%	0.76%
Year-End Interest Rate with Swaps (as a percent)	0.00%	0.00%